Recycling textile dyeing effluent through ozonation: An environmentally sustainable approach for reducing freshwater and chemical consumption and lowering operational costs

Dyeing operations in textile industries require large quantities of freshwater, which creates handling challenges and generates wastewater with high organic load that is difficult to treat and incurs high treatment costs. Minimizing freshwater consumption is essential for adopting sustainable practices. A limited number of studies are available in the literature exploring the possibility of recycling dyeing effluent through ozonation as an eco-friendly approach. Therefore, in the present work, the recycling of effluents obtained after dyeing with Reactive Red 198 (RR198) and Reactive Blue 21 (RB21) dyes through ozonation treatment has been studied. Nearly complete decolourization with COD removal efficiency of 32 % was obtained for both dye effluents after 15 min of ozonation. The qualities of recycled dyed fabrics were compared to fresh water-dyed fabrics through spectrophotometric analysis and colour fastness tests. These qualities for both dyed fabrics with recycled effluent were found to be either in excellent or good category after each recycle. Comparative analysis of freshwater and chemical requirements, along with cost savings, was conducted over four dyeing attempts. The study revealed significant savings with recycled effluent dyeing including 60 % reduction in fresh water usage and 75 % in salt consumption compared to conventional freshwater dyeing. Thus, recycling textile dyeing effluent through ozonation treatment was found to be a resource efficient approach. This approach not only significantly reduces wastewater volumes but also freshwater demand without compromising the colour-related qualities of dyed fabrics. Additionally, it minimizes operational expenses, thereby, supporting textile industry's shift toward sustainable practices.